Movable rig and steering system

ABSTRACT

A drill rig with a steering system may include a substructure having a wheelhouse, a drill floor arranged atop the substructure, a mast extending upwardly and above the drill floor, and a steering system arranged within the wheelhouse. The steering system may include a wheel assembly comprising an electric motor configured for driving rotational motion of a wheel, a deployment device configuring for deploying the wheel assembly to carry the drill rig, and a steering mechanism configured for selective engagement with the wheel assembly and rotating the wheel assembly.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No. 15/349,661, filed Nov. 11, 2016, which is a continuation-in-part of U.S. patent application Ser. No. 15/285,946, filed Oct. 5, 2016, the disclosure of each are hereby incorporated by reference herein in their entirety.

FIELD OF THE INVENTION

The present application is generally directed to oil rig assemblies. Particularly, the present application relates to movable oil rig assemblies that may include moving systems and may be driven. More particularly, the present application relates to a movable rig having steerable wheel assemblies allowing for driving the rig in any direction.

BACKGROUND

Rigs drilling in the high Arctic may include sealed units to retain heat during drilling operations and rig moves. These rigs may move as a convoy of trailers towed by trucks and self-propelled units as they move between pads in the high Arctic. The typical rig move between pads may be several hundred yards or several miles. The complete rig may also move from well to well on the pad during drilling operations. During rig moves, the loads may be maintained below the tire capacity, bridge capacity, ice road capacity or other limiting factors. In some rigs, each of the 4 corners of the drilling modules may include 2 tires and two hydraulic drives all mounted onto a trunnion style suspension. The rig may include 4 trunnions in total and the rig may include a vertical hydraulic lift cylinder over each of the trunnions.

One style of rig for the Arctic drilling is a cantilevered style. In a cantilevered style rig, the drillfloor, mast, and well center may be cantilevered out over the well and wellhead to provide suitable vertical clearance for drilling operations. The cantilevered nature of the rig may enable the rig to traverse along a row of wells completing each well as it moves parallel to the wells.

These large drilling rigs and modules may be driven utilizing hydraulic motors. Hydraulic moving systems use several hundred gallons of hydraulic oil under pressures of 5000 psi and high flow rates to enable hydraulic motors to power each of the 8 tires. This hydraulic system may provide the tractive effort to move the rig. In an environmentally sensitive area such as the shoreline of the Arctic Ocean, the risk of a large environmental oil spill exists and may be caused by the high pressure and high flow rate of these hydraulic systems. The volume of hydraulic fluid used in these systems to move the rig is substantial and the risk of a hose failure or other substantial leak is great.

The steering mechanisms of these rigs may be known as Akermann steering and it may include a steering bar and hydraulic cylinders. This particular system of driving and steering can lead to tire scrubbing, notably while turning a corner, because the outside tires travel at a different RPM than the inside tires. These differing speeds of the tires at each corner of the drilling module cannot be controlled easily with hydraulics. Additional issues with the Akermann approach is that this steering system cannot rotate each of the 4 wheel sets 90 degrees without removal of the Akermann steering bar which can exceed 15 feet in length and 1000 pounds in weight. User intervention is commonly required and the Akerman steering bar is typically replaced with a different steering bar to provide for 90 degrees of travel. This current style of moving systems cannot enable the drilling module to travel at angles between the longitudinal direction and the transverse direction.

Current drilling modules have Akermann steering in the front and the back of the rig. The current steering geometry does not allow for the wheel sets at the front of the drilling module and the rear of the drilling module to steer together and point to one turn center for proper geometry, while the unit is negotiating a curve while travelling in a longitudinal direction. The turn center only works with current designs with either the front or rear steer acting alone, and pointing to the turn center, for proper geometry. This causes the turning radius of the drilling module vehicle to be larger, and more difficult to maneuver. Without proper steering on a tight curve, as the drilling module traverses the curve, tires may walk off the rims because each tire travels about a different center of rotation. This can be caused by the driver using both front and back steering mechanisms at the same time when each mechanism is not designed for such use. Thus, each tire follows a different radial path rather than a series of concentric radial paths that all converge to the same center point. The tire scrub produced by a lack of steering geometry with all wheel steering, can cause the tires to separate from the rims.

The tires on these rigs may be 40×57 tires and may have a pressure of 120 psi while loaded with over 100 tons per tire. Any excessive flexing of a tire while it is moving, produces heat. Excess heat can cause a tire failure. A tire failure of this size of tire could rupture the moving system hydraulic hoses, and cause an environmental spill on the tundra next to the Arctic Ocean. Moreover, this can result in a dangerous situation where, for example, an explosive tire deflation caused by tire/rim separation occurs and/or stability is reduced. In particular, where the rig includes a very tall vertically extending mast riding on it, the risk of overturning and catastrophic failure may be great. The overall height of the drilling module may exceed 230 feet and placing such a structure at risk of toppling is a grave concern.

SUMMARY

In one or more embodiments, an electric drive, hydraulic steer, moving system may enable a drilling rig with a gross vehicle weight of 1000 tons to be driven on 8 tires, utilizing its own power and in any direct. For example, the vehicle may be drive in any direction ranging from 0 to 90 degrees. The system may be capable of perfect steering while travelling in a longitudinal direction. The rig may also travel under its own power in a transverse direction. The rig may also travel under its own power at any angle between the transverse and longitudinal direction. At any direction past the longitudinal direction, the unit may include the ability for steering correction during this travel.

In one or more embodiments, a rig may include 8 AC electric motors driving 8 right angle gearboxes built into the trunnions, driving 8 planetary gearboxes which are bolted to the rims thus driving the 8 rim and tire assemblies. One drive unit per tire may be provided and each drive unit may be controlled independently. Each of the 4 corners of the drilling module may have 2 of these drives, one per tire, two tires per corner, and 8 tires total. The 8 AC electric motors may be controlled from a Variable Frequency Drive (VFD) house. The controls may be remote and wireless for the driver. The driver may walk alongside the drilling module and control the speed and the steering remotely. There may be 4 trunnions on the system such as one in each corner. The rig may have a vertical hydraulic lift cylinder over each of the trunnions. The AC motors may have electrical cables attached to them such that power may be drawn from drilling rig power such as a generator set inside the drilling module. With the VFD house and the controls for these motors, the unit may be programmed with constant torque in each of the wheels in order to balance the load and speed of each of the wheels as they negotiate a corner. In addition, the electronics may be capable of custom programming such that the speed can be controlled in the moving system to match or approach the safe working speed of the tires in the moving system. This may allow the tires to run safely and avoid overheating from excessive speed. Data may also be collected from this style of moving system. The data may include maximum speed, time travelled, and current load used. The data may be transmitted back to the drilling contractors main office for purposes of analysis and crew monitoring, for example. The moving system may also be governed to a selected speed for tire safety and heat dissipation.

The steering mechanism may include a linkage type of geometry having a double ended cylinder for driving the linkage and the wheel assemblies. This double ended cylinder assembly may be mounted inside a box that is free to travel up and down on 4 guides that have springs, hydraulic cylinders, or other biasing mechanisms on the bottom of the system. Thus, each steering cylinder may be free to travel up and down within its respective wheel assembly as the driller's side and off-drillers side hydraulic cylinders move up or down to lift or lower the load in order to achieve the final ride height of the drilling module. The springs or hydraulic cylinders may prevent the unit from bottoming out on a bottom stopper. The top of the guides may be attached to the body of the drilling module. The amount of hydraulics used to power the moving system may be much smaller than previous systems because less hydraulic fluid at slower speeds may be used to power the steering cylinder, lift cylinder, and the locking or engagement pins as compared to the drive systems of known rigs. The oil for these cylinders may not get as hot as the hydraulic drive moving systems and the cylinders may use a lower oil pressure of 3000 psi to operate and may not require a large volume flow rate.

The front and back steering may be set and/or controlled such that both units may point to one single turn center at the minimum possible turning radius. This is the point where proper steering geometry may be set for the rig, thus reducing tire scrub. Depending on the hole pattern in the steering system, the tire set may turn approximately 22.5 degrees when the drilling module is travelling in a longitudinal direction. All perpendicular radials from each tire may point to the same turn center, thus, resulting in a smooth turn and minimal steer cylinder force needed to make the turn.

For travelling longitudinally along a row of wells, the tires may be rotated 90 degrees on the centerline of each hydraulic lift cylinder using the double ended steering cylinder. For example, and as described in more detail below, the end of the barrel of the lift cylinder has a series of holes for the steering arm link to be capable of locking into any of the desired holes in this setup of holes. Once the maximum stroke is obtained from the steering cylinder, small cylinders connected to pins may disengage the pins from these holes at the end of the barrel. Using a guide, the steering arm link can be repositioned using the steering cylinder. Then the small cylinders connected to pins may reengage these pins in order to lock steering arm link to a new position. Thus the pair of wheels in each corner may be rotated to any angle so desired, such as 90 for transverse movement or 0 degrees for longitudinal movement, or any angle in between. This acts as a ratchet mechanism, and once the steering is set where the steering bars are symmetrical between the driller's side and off-drillers side, the rig may be moved under its own power. Since the steering mechanism is reset to symmetrical before travel, there exists the possibility of small steering adjustments with the steering mechanism, +/−1 to 2 degrees, in order to correct the location of the drilling module as it moves. This slight steering adjustment angle features locked stoppers, because the limit of steer may be 1 to 2 degrees. This degree of adjustment is small enough to avoid tire scrub, due to the very large turning radius in play and the short travel distance involved on a row of wells on a pad. In addition, since the steering arm is adjustable in any radial direction on the barrel of the lift cylinder, a right hand and left hand lift cylinder is not required for steering.

The moving system may perform opposite steering between front and back moving systems, such as when navigating a corner. That is, the front wheels may be turned toward the right and the rear wheels may be turned toward the left to allow the vehicle to navigate a right turn. This may occur on long road moves, for example. However, the system may also be capable of all 8 tires being pointed in the same direction in an angle between 0 degrees longitudinal and 90 degrees transverse, such as 45 degrees but not limited to this angle. Thus the entire drilling module may crab over at this angle while maintaining its longitudinal and transverse position as it travels. Since the steering mechanism is reset to symmetrical before travel, there exists the possibility of small steering adjustments with the steering mechanism, ±/−1 to 2 degrees, in order to correct the location of the drilling module as it moves. This slight steering adjustment angle features locked stoppers, because the limit of steer would be 1 to 2 degrees. This is small enough to avoid undue tire scrub due to the very large turning radius in play. This may occur over short travel distances such as on a row of wells, for example.

The moving system may additionally perform opposite steeling between adjacent wheels or adjacent wheel pairs by providing for individual rotation of each wheel or wheel pair. That is, the pins for a first pair of wheels may be disengaged from the holes at the end of the barrel of the lift cylinder, so as to disengage the steering arm link, while the pins for a second, adjacent pair of wheels may be engaged in one or more corresponding holes so for that lift cylinder so as to engage the steering arm link for that wheel pair. The steering cylinder may then be used to rotate the first of the two adjacent wheels pairs, while not rotating the second wheel pair. Once a desired rotation is obtained for the first wheel pair, the pins may be disengaged from that wheel pair, and pins may engage for the second wheel pair so as to allow for rotation of the second wheel pair. Once both sets of wheels are arranged in a desired rotational position, the pins may be reengaged for both wheel pairs in order to lock the steering arm link to a position. Thus two front wheel pairs and/or two rear wheel pairs may each be independently rotated to any angles desired, such as 90 for transverse movement or 0 degrees for longitudinal movement, or any angle in between.

Movement between wells may be done at the 90 degree position. This may save the rig from driving off of the well patterns and then backing up again. The wheelbase of the drilling module may be long and even with proper steering geometry at 22.5 degrees the maneuverability of this unit may be limited. With the wheels turned 90 degrees the drilling module is free to move sideways. The moving system does not have any pieces of equipment that need removal before turning the wheels 90 degrees, such as the removal of the Akermann steering bar, or the reinstallation of a different steering bar once the wheels are at 90 degrees. The entire process of repositioning the wheels under the drilling module can be done remotely by the operator in a safe environment with no overhead lifting of any of the components, and no one getting in between the tires.

The moving system at each end of the rig may also include vertical play of up to 6″ on each side in order accommodate any lack of levelness between the driller side and off-drillers side lift cylinders. The 4 lift cylinders may all be symmetrical with the adjustable steering arm pinning system, thus ensuring interchangeability with each other for spare parts or cylinder swapping.

In some embodiments, the moving system described herein for moving a rig may be used to move a support complex such as a mud system, pipeshed, or other system or device. The system may also be scalable for small rigs rather than large rigs. In still other embodiments, the moving system may be useable for desert rigs or large loads in the Middle East rather than Arctic applications.

BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter that is regarded as forming the various embodiments of the present disclosure, it is believed that the invention will be better understood from the following description taken in conjunction with the accompanying Figures, in which:

FIG. 1 is a perspective view of a drill rig and supporting systems, according to one or more embodiments.

FIG. 2 is a close-up view of the rig of FIG. 1 in isolation from the supporting systems, according to one or more embodiments.

FIG. 3 is a side view of the rig of FIGS. 1 and 2, according to one or more embodiments.

FIG. 4 is a perspective view of a wheelhouse portion of the rig of FIG. 1, according to one or more embodiments.

FIG. 5 is a perspective bottom view of the wheelhouse portion of FIG. 4, according to one or more embodiments.

FIG. 6 is a perspective bottom view of a pair of wheel assemblies of the wheelhouse of FIG. 4, according to one or more embodiments.

FIG. 7A is a perspective rear/left view of a pair of wheel assemblies in a drilling or retracted position, according to one or more embodiments.

FIG. 7B is a perspective front/left view of the pair of wheel assemblies of FIG. 7A, according to one or more embodiments.

FIG. 7C is a top view of the pair of wheel assemblies of FIG. 7A, according to one or more embodiments.

FIG. 7D is a right side view of the pair of wheel assemblies of FIG. 7A, according to one or more embodiments.

FIG. 7E is a front side view of the pair of wheel assemblies of FIG. 7A, according to one or more embodiments.

FIG. 7F is a left side view of the pair of wheel assemblies of FIG. 7A, according to one or more embodiments.

FIG. 8A is a perspective rear/left view of a pair of wheel assemblies in a driving or deployed position, according to one or more embodiments.

FIG. 8B is a perspective front/left view of the pair of wheel assemblies of FIG. 8A, according to one or more embodiments.

FIG. 8C is a top view of the pair of wheel assemblies of FIG. 8A, according to one or more embodiments.

FIG. 8D is a right side view of the pair of wheel assemblies of FIG. 8A, according to one or more embodiments.

FIG. 8E is a front side view of the pair of wheel assemblies of FIG. 8A, according to one or more embodiments.

FIG. 8F is a left side view of the pair of wheel assemblies of FIG. 8A, according to one or more embodiments.

FIG. 9A is a perspective rear/left view of a pair of wheel assemblies in a driving or deployed position and turned 90 degrees, according to one or more embodiments.

FIG. 9B is a perspective front/left view of the pair of wheel assemblies of FIG. 9A, according to one or more embodiments.

FIG. 9C is a top view of the pair of wheel assemblies of FIG. 9A, according to one or more embodiments.

FIG. 9D is a right side view of the pair of wheel assemblies of FIG. 9A, according to one or more embodiments.

FIG. 9E is a front side view of the pair of wheel assemblies of FIG. 9A, according to one or more embodiments.

FIG. 9F is a left side view of the pair of wheel assemblies of FIG. 9A, according to one or more embodiments.

FIG. 10A is a top view of a pair of wheel assemblies, according to one or more embodiments.

FIG. 10B is a top view of the pair of wheel assemblies of FIG. 10A where the wheels are turned 22.5 degrees relative to the position of FIG. 10A, according to one or more embodiments.

FIG. 10C is a top view of the pair of wheel assemblies of FIG. 10A where the wheels are turned 22.5 degrees relative to the position of FIG. 10B, according to one or more embodiments.

FIG. 10D is a top view of the pair of wheel assemblies of FIG. 10A where the wheels are turned 22.5 degrees relative to the position of FIG. 10C, according to one or more embodiments.

FIG. 10E is a top view of the pair of wheel assemblies of FIG. 10A where the wheels are in the process of turning the remaining degrees for a 90 degree turn relative to the position of FIG. 10A, according to one or more embodiments.

FIG. 10F is a top view of the pair of wheel assemblies of FIG. 10A where the wheels are turned 22.5 degrees relative to the position of FIG. 10D and 90 degrees relative to the position of FIG. 10A, according to one or more embodiments.

FIG. 11 is a perspective view of a pair of wheel assemblies according to one or more embodiments.

FIG. 12 is a perspective view of a pair of wheel assemblies according to one or more embodiments.

FIG. 13 is a perspective view of a pair of wheel assemblies according to one or more embodiments.

FIG. 14 is a perspective view of a pair of wheel assemblies according to one or more embodiments.

FIG. 15 is a perspective view of a pair of wheel assemblies according to one or more embodiments.

FIG. 16 is a perspective view of a pair of wheel assemblies according to one or more embodiments.

FIG. 17 is a top view of a pair of wheel assemblies according to one or more embodiments.

FIG. 18 is a rear view of a pair of wheel assemblies according to one or more embodiments.

FIG. 19 is a close-up view of a steering mechanism of a pair of wheel assemblies, according to one or more embodiments.

FIG. 20 is a perspective view of a pair of wheel assemblies according to one or more embodiments.

FIG. 21 shows a method of driving and/or steering a drill rig, according to one or more embodiments.

FIG. 22 is a top view of a pair of wheel assemblies, according to one or more embodiments.

FIG. 23 is a top view of two pairs of wheel assemblies of a drill rig, the wheel assemblies arranged in a rotational configuration for rotating the rig about a central axis, according to one or more embodiments.

FIG. 24A is a top view of two pairs of wheel assemblies of a drill rig, according to one or more embodiments.

FIG. 24B is a top view of the two pairs of wheel assemblies of the drill rig of FIG. 24A, where the wheels are turned inward approximately 80.35 degrees relative to the position of FIG. 24A, according to one or more embodiments.

FIG. 24C is a top view of the two pairs of wheel assemblies of the drill rig of FIG. 24A, where the drill rig is rotated about its central axis, according to one or more embodiments.

FIG. 25 shows a method of rotating a drill rig about a central axis, according to one or more embodiments.

FIG. 26 is a top view of a drill rig rotating about a central axis, according to one or more embodiments.

DETAILED DESCRIPTION

The present application, in one or more embodiments, relates to a moving system for a drill rig. In particular, the moving system may be an electrically driven system having a steering mechanism providing for a high level of directional range of motion allowing for travel at 90 degrees relative to a primary direction, for example. The moving system may be operated completely automatically without the need for physical intervention or adjustment by operators making the system easier to use and safer to operate. The steering mechanism may be configured to accommodate various radii turns and may allow for coordinated steering between the front and rear mechanisms thereby avoiding tire scrub and further avoiding having tires walk off of rims or other dangerous conditions. The electrically driven system may provide an alternative to high pressure, high flow, hydraulic drive systems and thereby may reduce the risks of environmental effects associated with hydraulic failures and, in particular, hydraulic fluid leaks. The flexibility of the present drive system allows for a high level of rig moving versatility and positioning advantage.

With reference to FIG. 1, a drill rig assembly 100 is shown. The drill rig assembly 100 may include a drill rig portion 102 and various assemblies and systems 104 for supporting drilling operations. In particular, the assemblies and systems 104 may include a pipeshed, a mud tank module, a mud pump module, a power module, and a cutting module. Still other facilities and systems may be provided. In some embodiments, the drill rig 102 and supporting assemblies and systems 104 may be configured for arctic operations and, as such, may be partially or fully enclosed. In FIG. 1, the drill floor 106 and mast 108 of the drill rig 102 is shown in a cantilevered condition. That is, the drill rig 102 may include a cantilevering rail system 110 allowing the drill floor 106 and mast 108 to shift laterally relative to a supporting structure of the rig 102 such that drilling operations may be performed in an offset position relative to the supporting structure.

FIG. 2 shows the drill rig in isolation from the other supporting assemblies and systems. In FIG. 2, the rig 102 has been shifted back from its cantilevered condition and is being viewed from the rear of FIG. 1, for example. Of particular note with respect to the present application is the presence of a wheelhouse 112 on each of the front or cab end 114 and rear or well end 116 of the rig 102. Each wheelhouse 112 may be configured to enclose a moving system 118. In particular, the wheelhouse 112 may function to support the rig 102 during drilling operations and may provide for deployment of a moving system 118 allowing the rig 102 to be picked up and supported by the moving system 118 for purposes of transport between drilling locations. A side view of the drill rig 102 is shown in FIG. 3 where it can be seen that a front cab 120 or drive location may be provided extending from the front 114 of the rig. It is to be appreciated that while an operator may drive the rig 102 from the front cab 120, the automated nature of the system may also allow the operator to drive the rig 102 from outside the rig 102 such as, for example, while walking with the rig 102 and monitoring the position of the rig 102 relative to the travel path or roadway or monitoring the rig 102 relative to a drilling location or well center. In this embodiment, the operator may use a tablet or other mobile computing device such as an ipad or other computing device having a moving system interface.

FIG. 4 shows a wheelhouse 112 in isolation from the rig 102. The wheelhouse 112 may be configured to support the rig 102 and enclose the moving system 118, while allowing for deployment of the moving system 118 to move the rig 102. The wheelhouse 112 may include a rig interface 122, a cage or truss walls portion 124, and a foot or bearing pad portion 126. As shown, the moving system 118 may be arranged within the truss walls 124 and may have a deployed position where a bottom of the moving system 118 is below the bearing pad 126 and a retracted position where a bottom of the moving system 118 is at or above the bearing pad 126. As such, when the moving system 118 is deployed, the rig 102 may be fully supported by the moving system 118 and the bearing pad 126 may be raised off of the ground. When the moving system 118 is retracted, the bearing pad 126 may be in contact with the ground to support the rig 102 during drilling operations.

As discussed, the bearing pad 126 of the wheelhouse 112 may be configured to support the rig 102 during drilling operations. The bearing pad 126 may extend around all or a portion of the wheelhouse 112. In some embodiments, the bearing pad 126 may extend along each of two sides of the wheelhouse 112 or it may extend along each of four sides. The bearing pad 126 may be attached to a bottom of the truss walls 124 and may be configured to receive rig loads from the truss walls 124 and transfer rig loads to the ground. The bearing pad 126 may include a relatively flat ground-contacting surface configured for distributing loads to the surface of the ground. The bearing pad 126 may be relatively plate like and may have a tapered shape where the pad is thinner near its outer edges and thicker near its inner portion so as to accommodate shear and bending forces resulting from rig loads. In some embodiments, the tapered shape may be provided in the form of stiffeners arranged on a relatively flat constant thickness plate rather than varying the thickness of the plate. In some embodiments, a combination of both may be provided. The bearing pad 126 may be pivotally connected to the truss walls 124 to accommodate unevenness in the ground or the bearing pad 126 may be more rigidly connected as shown.

The truss walls 124 may extend upwardly from the bearing pad 126 to form a surrounding structure to house the moving system 118. The truss walls 124 may include a plurality of upright support elements and a series of diagonal and/or cross braces. In some embodiments, the series of diagonal and/or cross braces may be removable so as to allow access to the moving system 118 and allow for maintenance and/or repair. For example, one or more diagonal and/or cross braces may be removed to allow for tire changing or repair.

With reference to FIGS. 5 and 6, the rig interface 122 of the wheelhouse 118 may include a relatively flat roof-like structure supported by the truss walls 124 and extending across the top of the moving system 118. The rig interface 122 may be structurally designed to receive rig loads and transfer them to the supporting structure. In some conditions of use, the supporting structure may include the truss walls 124 of the wheelhouse 112 when the moving system 118, for example, is not deployed. In other conditions of use, the supporting structure may include the moving system 118 when, for example, the moving system 118 is deployed. The rig interface 122 may include a series of cross members extending across the wheelhouse 112 and above the moving system 118 from one side of the truss walls 124 to an opposing side, for example. The rig interface 122 may include one or more cover plates or surfaces above and/or below the cross members. In one or more embodiments, the rig interface may include a deployment point or points 128 and a steering control point 130. The deployment point or points 128 may include locations where jacking cylinders may engage the rig interface 122 to deploy the moving system. In one or more embodiments the cross members may be arranged to extend across the wheelhouse 112 so as to pass above the deployment point 128 and, as such, allow for connection of the jacking cylinder to the cross member. In some embodiments, the cross members may drop near the deployment point 128 so as to increase the strength of the cross members and accommodate the high loads imparted when the moving system 118 is deployed. The steering control point 130 may include a location of attachment for a steering mechanism and may provide a reference point for lateral shifting and/or movement used in steering the moving system 118.

As mentioned, the moving system 118 may be housed within the above-described wheelhouse 112. The moving system 118 may be configured for deployment from the wheelhouse 112 and retraction within the wheelhouse 112. The moving system 118 may also be configured to move the rig 102 in a selected direction and may further allow for steering the rig 102 while moving and/or otherwise adjusting the direction of travel of the rig 102 before beginning travel in that particular direction. The moving system 118 may include a pair of same or similar wheel assemblies 132 arranged substantially adjacent to one another within the wheelhouse 112. In some embodiments, more or fewer wheel assemblies 132 may be provided. The moving system 118 may also include a steering system 134 for steering the wheel assemblies 132 relative to the rig 102 and allowing the direction of travel to be controlled.

The wheel assemblies 132 may be configured for rolling engagement with the ground to allow the rig 102 to move and may also be configured for rotation about a substantially vertical axis 136 to accommodate steering of the rig 102. In one or more embodiments, the wheel assemblies 132 may each include a central core element 138, an outer wheel system 140 arranged to an outer side of the central core element 138 and an inner wheel system 142 arranged to an inner side of the central core element 138. The wheel assemblies 132 may also each include a jacking element 144 arranged between outer and inner wheel systems and between the core element 138 and the rig interface 122.

With reference now to FIG. sets 7A-7F, 8A-8F, and 9A-9F, each of the outer wheel system 140 and inner wheel system 142 may each include a wheel 146 offset from the central core portion 138 and an electric drive motor 148 arranged on the central core portion 138. The wheels 146 may be arranged adjacent to the central core portion 138 to form a pair of wheels. The electric drive motors 148 may be configured to impart rotational force to their respective wheels 146 to drive the rig 102. The electric drive motors 148 may be arranged vertically between the inner and outer wheels of each wheel assembly 132 and may include a vertically extending drive shaft. The drive shaft may extend downwardly into the central core 138 portion. The central core portion 138 may include a right angle gear box. The gear box may be connected to a planetary gear system that may be provided to drive a respective wheel arranged in a substantially vertical plane. The wheels 146 may be supported relative to the central core portion 138 by the planetary system, which may be bolted to a substantially horizontally extending trunnion axle supported off of the central core 138 portion by a pin. The trunnion axle may allow the pair of wheels 146 to function together and accommodate uneven surfaces where the trunnion axle may be able to rotate about a longitudinal substantially horizontal axis defined by its supporting pin.

A jacking or deployment system 144 may be arranged on the central core portion 138 between the inner and outer wheel and may extend upwardly from the central core portion 138 to engage the rig interface portion 122 of the wheelhouse 112. The jacking or deployment system 144 may be configured to extend a respective wheel assembly 132 away from the rig interface 122 beyond the foot 126 of the wheelhouse 112 thereby deploying the wheel assembly 132 for use. The jacking or deployment system 144 may include a hydraulic cylinder system. The hydraulic cylinder may be arranged such that the base or cap of the cylinder is secured to the central core portion 138 and rod portion extends upwardly therefrom to the rig interface 122. The rod portion may include a flange plate and may be secured to rig interface 122 at a deployment point 128. As the cylinder is actuated, the rod portion may extend out of the barrel thereby elongating the cylinder and driving the central core portion 138 away from the rig interface 122.

The jacking or deployment system 144 may be a non-keyed cylinder such that the rod is free to rotate relative to the barrel, for example. As will be explained in more detail below, the steering system 134 may engage the barrel portion of the jacking or deployment system 144 so as to rotate the barrel relative to the rod and, thus, rotate the wheel assemblies 132. As part of the engagement of the steering system 134, the cylinder head of the jacking system 144 may include a plate or a series 150 of plates to be engaged by the steering system 134.

In one or more embodiments, the plate or series of plates 150 may include a sandwich plate including a pair of plates spaced apart from one another and configured to receive a portion of the steering mechanism therebetween. The pair of plates 150 may be generally or substantially annular in shape allowing the rod and/or the barrel of the jacking cylinder 144 to pass therethrough. The pair of plates 150 may be rigidly secured to the barrel of the jacking cylinder 144 such that rotational forces applied to the pair of plates 150 may impart rotational motion on the wheel assembly 132 relative to the jacking rod 144 and the rig 102. In some embodiments, the pair of plates 150 may be directly secured to the barrel of the jacking cylinder 144. In other embodiments, the separation of the pair of plates 150 may be created by a bushing or collar arranged on and secured to the barrel of the cylinder and the plates 150 may be secured thereto. In either case, the cylindrical element extending between the pair of plates 150 may define a neck having a substantially circular shape and having an outer diameter. In some embodiments, the plates 150 may be arrange one above the other and the space between the plates may be sufficient to receive a jaw plate of the steering system as described in more detail below.

The pair of plates 150 may include a series of holes or apertures 152 for receiving an engagement pin 154. The plates 150 may be arranged in spaced apart position and the holes 152 in one plate may be aligned with holes 152 in the other plate 150. The holes 152 in the pair of plates 150 may be arranged to accommodate particular angular motions or rotations of the wheel assembly 132. In some embodiments, the holes 152 may be arranged in an annular array or row along a circular centerline of the annular plate. In some embodiments, the holes 152 may be in multiple rows and may be staggered from one row to another row. Still other arrangements of holes 152 may be provided. In some embodiments the holes 152 in a particular row may be spaced from one another such that adjacent holes are approximately 10 degrees, 22.5 degrees, 30 degrees, 45 degrees, 90 degrees, or other angles apart from one another. Still other angular spacings may be provided.

In some embodiments, the wheels may be sized to accommodate a 1000 ton rig. Where eight wheels are provided, each wheel may be configured to support 250,000 pounds. In some embodiments, the tires may be 40×57, for example, and may include a tire pressure of approximately 120 psi. Other tires sizes may be used.

Having discussed the wheel assemblies 132 in great detail, it is noted that adjacent wheel assemblies 132 may be spaced from one another sufficiently to allow for full rotation or at least 90 degrees of rotation. The wheel assemblies 132 may, thus, be spaced from one another a distance equal to one wheel diameter and, in some embodiments, 1¼ or 1½ wheel diameters. The wheelhouse 112 may be sized accordingly, and may also provide sufficient clearance around the wheel assemblies 132 to allow for full rotation or at least 90 degrees of rotation of the wheel assemblies 132.

With reference to FIGS. 10A-10F, the moving system 118 may include a steering system 134 configured for controlling the planetary orientation of the wheel assemblies 132 and, as such, the travel direction of rig. The steering system 134 may include a control device 156, a linkage assembly 158, and a wheel assembly engaging portion 160. The steeling system 134 may be connected to the rig interface 122 portion of the wheelhouse 112 and, as such, may forcibly impart rotational motion of the wheel assemblies 132 relative to the rig 102.

The control device 156 may be configured for actuating motion of the wheel assemblies 132 and may be further configured to do so in the deployed and/or retracted position. The control 156 device may, thus, include an actuating portion 162 for actuating steering motions and a guide system 164 allowing the control device 156 to track and/or follow the deployment and retraction of the wheel assemblies 132. The control device 156 may be positioned between the one or more wheel assemblies 132 and may be configured to simultaneously control the orientation of the wheel assemblies 132 such that a change in orientation of one wheel assembly 132 is correspondingly changed in the other wheel assembly 132.

The guide system 164 of the control device 156 may include one or a series of guides such as guide rods 165 secured to the steering control point 130 and extending downwardly from the steering control point 130. The guide system 164 may include a housing 166 arranged on the guide rods 165 and configured for sleevably travelling up and down along the length of the guide rods 165. The guide rods 165 may include one or more biasing elements 168 arranged thereon and configured for biasing the housing 166 in an upward position. In some embodiments, the biasing elements 168 may include springs concentrically arranged on the guide rods 165 and biased between a guide rod flange and the housing 166. In other embodiments, the biasing elements 168 may be hydraulic cylinders that may be actuated to control the position of the control device. In other embodiments, the control device may be free floating using counter-weights and pulleys, instead of cylinders or springs. In this embodiment, it may function as a weightless component within the suspension, as the suspension system moves over uneven terrain. In the case of biasing elements, such as springs, the biasing elements 168 may be relatively stiff, but may have a stiffness that is overcome when the wheel assemblies are moved to a deployed position. The length of the guide assemblies may be such that the control system 156 may move a distance away from the rig interface 122 that is substantially the same as the deployment distance of the wheel assemblies 132. That is, a stroke length of the housing 166 along the guide system 164 may be the same or similar to the stroke length of the jacking or deployment cylinder 144 of the wheel assembly 132 such that the control system 156 may move together with the deployment of the wheel assemblies 132.

The actuating portion 162 of the control device 156 may include a laterally moving mechanism that may push on one wheel assembly 132 while pulling on another wheel assembly 132. The actuating portion 162 may be offset rearward or forward from a laterally extending centerline of the wheel assemblies 132 and by pushing/pulling on the wheel assemblies (i.e., from side to side in FIG. 10A), the actuating portion 162 may create a torsional or torque force on the wheel assemblies 132 causing them to rotate. By virtue of being positioned between the assemblies 132, the push/pull of the actuating portion 162 may cause each wheel assembly to rotate in the same direction. (i.e., clockwise or counter clockwise in FIG. 10A).

The actuating portion 162 may include a double-ended cylinder. The double-ended cylinder may include a barrel having a rod extending from each end where extension of a rod out one side of the barrel may simultaneously cause retraction of a rod into the other side of the barrel. In some embodiments, the actuating portion may include a rack and pinion driven by an electric or hydraulic motor, for example. In the case of the double-ended cylinder, the amount of extension of the rod out of or into the barrel may provide for a partial rotation of a wheel assembly 132. For example, the extension of the rod out of or into the barrel may create rotation of a wheel assembly 132 less than the full available rotation of the wheel assembly 132. Further rotation of the wheel assembly may be provided for by disengaging the actuation portion 162 from the wheel assembly 132, retracting the rod (or extending the rod as the case may be), reengaging the actuation portion 162 with the wheel assembly 132 and further rotating the wheel assembly 132. Accordingly, the stroke of the cylinder may be less than that which may be used to induce a larger rotation, for example.

A linkage assembly 158 may extend from each end of the actuating portion 162 and may be configured to transfer the lateral force and motion from the actuating portion 162 to the wheel assembly engaging portion 160 while accommodating the rotation of the engaging portion 160. The linkage assembly 158 may include a laterally extending bar 170 having a first jaw connection at the rod of the actuating portion 162 and a second jaw connection at the wheel assembly engaging portion 160. In some embodiments, the bar 170 may be a solid bar or a hollow bar, such as a pipe or tube. The bar 170 may be pivotally connected to the rod with a pin or other pivotal connection and may similarly be connected to the wheel assembly engaging portion with a pin or other pivotal connection.

The wheel assembly engaging portion 160 may engage the wheel assembly 132 and transfer forces from the actuation portion 162 to induce rotational motion of the wheel assembly 132. The engaging portion 160 may be configured for selectively engaging the wheel assembly allowing for a ratcheting, stepping, or incremental approach to rotating the wheel assembly 132. The engaging portion 160 may include a jaw plate 172 configured for selective engagement with the jacking or deployment cylinder 144. In particular, the jaw plate 172 may be configured for engagement with the jacking or deployment cylinder 144 at or near the cylinder head of the barrel of the jacking cylinder 144. As such, the engaging portion 160 may be configured to cause the barrel portion of the jacking cylinder 144 to rotate relative to the rod portion thereof thereby causing the wheel assembly 132 to rotate.

The jaw plate 172 may extend from the linkage assembly 158 and may be configured to engage the sandwich plates 150 arranged at or near the cylinder head of the jacking cylinder 144. The jaw plate 172 may be substantially planar so as to slidably engage the pair of plates 150 and allow for relative rotation of the jaw plate 172 between the pair of plates 150. When viewed from above, the jaw plate 172 may define a jaw or an inner radiused surface 173 configured for abuttingly engaging the neck extending between the pair of plates 150. The inner radiused surface 173 may extend around the neck to a point just past the half-way point and may then divert from its path along the neck outwardly. The engaging portion 160 may also include a closure plate 174 extending across the open end of the jaw plate 172 on an opposing side of the neck. The closure plate 174 may include an inner radiused surface 175 configured for abuttingly engaging the neck. Accordingly, the jaw plate 172 and the closure plate 174, together, may extend the full circumference of the neck area between the pair of plates 150. The closure plate 174 may be pinned bolted or otherwise secured to the jaw plate 172 on each side and may be removable as required for removal of the steering mechanism 134 from the wheel assembly 132.

The jaw plate 172 may include a pair of engagement holes 176 configured for engagement by the engagement or locking pins 154. The engagement holes 176 may be arranged on either side of the neck at or near opposite sides of the neck. In some embodiments, as shown, the engagement holes 176 may be arranged 180 degrees from one another and along a centerline extending through the holes 176 and through the center of the jacking cylinder 144. The engagement holes may be arranged along a circle having a radius that is the same or similar to the radius of the row or rows of holes 152 in the pair of plates 150. As such, the engagement holes 176 may be configured to align with a corresponding pair of holes 152 in the pair of plates 150.

The engagement or locking pins 154 may be arranged in the pair of holes 176 of the jaw plate 172 and in the holes 152 in the pair of plates 150. That is, each pin 154 may extend upwardly through a lower plate of the pair of plates 150, through the jaw plate 172, and through an upper plate of the pair of plates 150. As shown, an engagement pin 154 may be provided corresponding to each of the engagement holes 176 and, as such, the jaw 172 plate may be configured for rotational engagement with the pair of plates 150 via the engagement pins 154.

The engagement pins 154 may be actuatable pins such that the jaw plate 172 may selectively engage the pair of plates 150 and selectively impart rotational motion in the pair of plates 152 and, thus, the corresponding wheel assembly 132. The engagement pins 154 may include a hydraulic cylinder 178 that may be controlled to engage and disengage the pins 154 from the holes 152 in the pair of plates 150 and the jaw plate 172. By way of controlling the hydraulic cylinder 178 the pins 154 may be selectively engaged or disengaged from the holes 150/176. In some embodiments, the hydraulic cylinder 178 may be actuatable only in conditions of rotation that allow for hole alignment. For example, upon disengaging the pins 154, the pins 154 may not be actuatable unless/until a rotation substantially equal to the radial position of the holes 152 in the pair of plates 150 is turned by the jaw plate 172. In other embodiments, no limitation on the timing of the hydraulic cylinder 178 may be included.

In some embodiments, the engagement pins 154 may be integral to steering operations and may allow for a ratcheting, stepping, and/or incremental steering operation. That is, with the engagement pin 154 in place, the actuating portion 162 of the steering system 134 may shift laterally to impart rotation in the wheel assemblies 132. Once the actuating portion 156 has passed through a selected stroke length, the actuating portion 162 may stop, the engagement pin 154 may be disengaged from the jaw plate 172 and the pair of plates 150 and the actuating portion 162 may return to its position before the selected stroke length. The engagement pin 154 may be reengaged with the jaw plate 172 and the pair of plates 150 and the process may be repeated to further rotate the wheel assembly 132. Depending on the stroke length of the actuating portion 156 and the radial spacing between the holes 152 in the plates 150, the steering or wheel assembly rotation may be performed in resulting increments. Still further, the wheel assemblies 132 may be capable of rotation that is not limited by the stroke length of the actuating portion 162 or by other features. In some embodiments, the wheel assemblies 132 may be rotated up to 90 degrees, up to 180 degrees, up to 270 degrees, or up to 360 degrees.

With continued reference to FIGS. 10A-10F and FIG. 21, a method may be described for rotating one or more wheel assemblies 132. As shown in FIG. 10A, the wheel assemblies 132 may be positioned in a substantially longitudinal direction. In some cases, particularly when it is desirable to move a rig 102 along a series of wells, an operator may wish turn the wheel assemblies 90 degrees with or, more likely, without moving the rig 102. By comparing FIGS. 10A and 10B, it is apparent that both wheel assemblies 132 in FIG. 10B have rotated approximately 22.5 degrees about the jacking/deployment cylinder 144 relative to that shown in FIG. 10A. The underlying method to arrive at the condition of FIG. 10B may include disengaging the engagement pins 154 of the wheel assembly engagement system 160 from each pair of plates 150 and jaw plate 172, allowing the plate systems to rotate freely relative to one another without rotating the wheels 132. The actuating portion 162 of the control device 156 may then be activated by shifting it to the left from its position in FIG. 1.0A, thereby extending the hydraulic rod out of the left of the barrel and retracting the hydraulic rod into the right of the barrel. The particular amount of shift may be sufficient to rotate each plate system approximately 22.5 degrees. At that point, the engagement pins 154 of the wheel assembly engagement system 160 may be reengaged with the pair of plates 150 and the jaw plate 172. The actuating portion 162 may then be shifted back to the right thereby retracting the left rod and extending the tight rod and returning the position of the jaw plate back 172 to its position of FIG. 10A so as to rotate the wheel assemblies 132 approximately 22.5 degrees. By comparing the wheel assemblies 132 of FIG. 10B to those of FIG. 10C, it is apparent that the wheel assemblies 132 of FIG. 10C have rotated yet another 22.5 degrees relative to the position of the wheel assemblies 132 of FIG. 10B. The process for creating this rotation and having the control device 156 return to the position shown in FIG. 10C may be the same or similar to that described for the transition between FIGS. 10A and 10B. The process may again be repeated to create the condition shown in FIG. 10D and the process may be repeated again to create the condition shown in FIG. 10F. FIG. 10E shows an intermediate position between the positions of FIGS. 10D and 10F and shows the actuating portion 162 shifted to the left as described above.

It is to be appreciated that, alternatively, the transitions illustrated between each of FIGS. 10A through 10F may be achieved by actuating the actuating portion 162 before disengaging the engagement pins 154 for each rotation of the wheels 132. For example, the method to transition from the position show in FIG. 10A to the position shown in FIG. 10B may include first actuating the actuating portion 162 by shifting it to the right from its position of FIG. 10A so as to rotate the wheel assemblies 132, disengaging the engagement pins 154 from the plates 150 and jaw plate 172, shifting the actuating portion 162 back to the left so as to return the position of the jaw plate back 172 to its position of FIG. 10A without rotating the wheels 132, and reengaging the engagement pins 154.

In one or more embodiments a method 200 of operating a drive system of a rig may include deploying a wheel assembly from a drill rig. (202) The method 200 may also include activating the actuating port of the control device by shifting it to the left or right from its position in FIG. 10A to rotate a wheel assembly. (204) For purposes of allowing for further rotation, the method may also include disengaging the pins of the wheel assembly engagement system from the pair of plates and the jaw plate (206), shifting the actuating portion back to the tight or left (opposite the initial direction) back to its position of FIG. 10A without rotating a wheel assembly (208), and reengaging the locking or engagement pins into the pair of plates and the jaw plate (210). The method may also include repeating or reversing these steps to further rotate the wheel assembly or reverse the direction of rotation. (212) The method may also include actuating an electric drive motor to drive a wheel of the wheel assembly. (214) In one or more embodiments, the method may also include coordinating drive speeds of one or more wheel assemblies (216) and/or coordinating wheel torques of one or more wheel assemblies (218). It is to be appreciated that the method steps included herein may be performed in one of several available orders and the order is not to limited to the order shown in FIG. 21.

FIGS. 11-20 show additional perspective views of pairs of wheel assemblies according to embodiments of the present application.

In some embodiments, wheel assemblies of the present disclosure may provide for rotation of a drill rig about a central axis of the rig so as to change direction without, or substantially without, changing location of the rig. The wheel assemblies may be generally rotated inward, such that a pair of wheel assemblies controlled by a same steering system are rotated in opposing directions. In some embodiments, this may be accomplished by separately rotating the wheel assemblies. Turning now to FIG. 22, a pair of wheel assemblies 332 coupled to a steering system 334 is shown in a position configured for rotating a drill rig. As shown, each wheel assembly may have an inner wheel 342 and an outer wheel 340 rotated inward toward a center of the rig. In some embodiments, each wheel assembly 332 may be rotated approximately 80.35 degrees in some embodiments. In other embodiments, the wheels assemblies 332 may be rotated to a different degree of rotation so as to be configured about a central axis of the rig. Generally, the degree of rotation may relate, at least in part, to a distance between wheel assemblies 332. By rotating each of the wheel assemblies 332 inward in this way, the rig may be capable of turning about itself at a central axis so as to change direction. For example, FIG. 23 shows four wheel assemblies 332 of a drill rig coupled to two steering systems 334. The wheel assemblies 332 of FIG. 23 are shown in a position configured for rotating the drill rig about a central axis 333.

As shown in FIG. 22, the steering system 334 may include a control device 356 for actuating motion of the wheel assemblies 332, a pair of linkage assemblies 358 extending from the control device toward each of the wheel assemblies, and wheel assembly engaging portion 360 coupled to each wheel assembly. Each wheel assembly engaging portion 360 may have jaw plate 372 configured to engage one or more sandwich plates 350, as described above. Moreover, a pair of actuatable engagement pins 354 may be configured to engage the jaw plate 372 and/or sandwich plates 350. To achieve a desired angle of rotation of the wheel assemblies 332 so as to angle the wheels about a central axis of the rig, in some embodiments, the wheel assembly engaging portion 360 may have a locking pin 355. The locking pin 355 may operate similar to engagement pins 354, but may be arranged at an angle different than that of engagement pins 354. That is, for example, the locking pin 355 may be arranged at an angle of approximately 12.85 degrees from a nearby engagement hole of the jaw plate 372. In this way, the locking pin 355 may provide for an alternate degree of rotation than that provided by the engagement pins 354 (i.e. a degree of rotation in an increment not based on evenly spaced holes in the sandwich plates 350.) The position of the locking pin 355 may be selected so as to provide a degree of rotation that accommodates the wheel assembly 332 position. That is, the wheel assembly 332 position may define a diameter with a degree of curvature which, in turn, may define the degree of rotation of the wheel assemblies 332. When the locking pin 355 is actuated to engage an engagement hole in the jaw plate 372 and/or sandwich plates 350, the engagement pins 354 may be disengaged, and vice versa.

With reference to FIGS. 24A-24C and 25, a method may be described for rotating one or more wheel assemblies 332 to a rig rotation position. As shown in FIG. 24A, the wheel assemblies 332 may be positioned in a substantially longitudinal direction. In some cases, particularly when the rig approaches a tight corner as shown in FIG. 24A, an operator may wish to rotate the rig about a central axis 333 of the rig in order to alter direction of travel. By comparing FIGS. 24A and 24B, it is apparent that all four wheel assemblies 332 in FIG. 24B have rotated inward at approximately 80.35 degrees about the jacking/deployment cylinders relative to that shown in FIG. 24A. In other embodiments, the four wheel assemblies 332 may be rotated inward at any other suitable degree of rotation about the jacking/deployment cylinders. The underlying method to arrive at the condition of FIG. 24B may include separately rotating each wheel assembly 332 by actuating the steering systems 334. That is, for a pair of wheel assemblies 332, the engagement pins 354 and/or locking pin 355 may be disengaged from one or both wheel assemblies. The steering system 334 may then be actuated to rotate one of the wheel assemblies by shifting the actuating portion 362 to the left or right (as needed to bring the wheel assembly 332 inward) and engaging the engagement pins 354 and/or locking pin 355 in the sandwich plates 350 and jaw plate 372. The engagement pins 354 and/or locking pin 355 may then be disengaged from the rotated wheel assembly 332 and may operate with the actuating portion 362 to rotate the second wheel assembly of the pair of wheel assemblies. As shown in FIG. 24C, once each wheel assembly 332 has been rotated, the an electric drive motor may be actuated to drive the wheel assemblies so as to rotate the drill rig about a central axis.

In one or more embodiments a method 400 of operating a drive system of a rig may include deploying a pair of wheel assemblies from a drill rig. (402) The method 400 may also include disengaging the pins of the wheel assembly engagement from the pair of plates and jaw plate for at least one wheel assembly of the pair of wheels assemblies. (404) The method may include activating the actuating portion of the control device by shifting it to the left or right to rotate a first wheel assembly without rotating a second wheel assembly. (406) The method may include disengaging the engagement pins and/or locking pin from the first wheel assembly once the first wheel assembly is rotated to desired degree of rotation. (408) In some embodiments, only the locking pin may be used to engage the sandwich plates and jaw plate to rotate a wheel assembly. In other embodiments, the engagement pins may be engaged first for one or more rotations, followed by engagement of the locking pin for one or more rotations to achieve a final desired degree of rotation. In this way, the rotation of a wheel assembly may be an iterative process involving the engagement pins and/or the locking pin. Once the desired degree of rotation is achieved in the first wheel assembly and the pins are disengaged from the first wheel assembly, the engagement pins and/or locking pin may engage the second wheel assembly (410), and the actuating portion may be activated by shifting it to the left or right to rotate the second wheel assembly. (412) Once the second wheel assembly is rotated to a desired degree of rotation, the engagement pins and/or locking pin may be reengaged with the first and/or second wheel assemblies. (414) Once again, an iterative process of multiple rotations using the engagement pins and/or the locking pin may be used to achieve the desired degree of rotation. The method may also include repeating or reversing these steps to further rotate the wheel assembly or reverse the direction of rotation. (416) The method may also include actuating an electric drive motor to drive one or more wheels of the wheel assemblies. (418) in one or more embodiments, the method may also include coordinating drive speeds of one or more wheel assemblies (420) and/or coordinating wheel torques of one or more wheel assemblies (422). It is to be appreciated that the method steps included herein may be performed in one of several available orders and the order is not to be limited to the order shown in FIG. 25.

The systems and methods described with respect to FIGS. 22-25 provide improvements over conventional drill rig steering systems. These systems and methods allow a rig to be rotated about a central axis in order to negotiate relatively sharp turns or corners and generally without the need for excessive repositioning of the rig. That is, under conventional steering systems, such as a rack-and-pinion-type steering system, changing direction of a drill rig may generally require either a large turning radius or a relatively large number of forward and backward movements. In contrast, methods and systems of the present disclosure may allow a drill rig to rotate about itself, without the need for a large turning radius and without the need for excessive forward and backward movements of the rig. By the use of pins and selectable engagement holes at each wheel, wheel assemblies of the present disclosure may be individually rotated, such that two wheels coupled to the same actuating device may be turned in opposing directions, thus allowing for rotation of the entire rig. This is a great improvement over conventional rig steering systems.

FIG. 26 illustrates a drill rig 500 having two pairs of wheel assemblies 532 in a rotational configuration such that the drill rig may rotate about a central axis to change direction of travel.

As used herein, the terms “substantially” or “generally” refer to the complete or nearly complete extent or degree of an action, characteristic, property, state, structure, item, or result. For example, an object that is “substantially” or “generally” enclosed would mean that the object is either completely enclosed or nearly completely enclosed. The exact allowable degree of deviation from absolute completeness may in some cases depend on the specific context. However, generally speaking, the nearness of completion will be so as to have generally the same overall result as if absolute and total completion were obtained. The use of “substantially” or “generally” is equally applicable when used in a negative connotation to refer to the complete or near complete lack of an action, characteristic, property, state, structure, item, or result. For example, an element, combination, embodiment, or composition that is “substantially free of” or “generally free of” an ingredient or element may still actually contain such item as long as there is generally no measurable effect thereof.

In the foregoing description various embodiments of the present disclosure have been presented for the purpose of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise form disclosed. Obvious modifications or variations are possible in light of the above teachings. The various embodiments were chosen and described to provide the best illustration of the principals of the disclosure and their practical application, and to enable one of ordinary skill in the art to utilize the various embodiments with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the present disclosure as determined by the appended claims when interpreted in accordance with the breadth they are fairly, legally, and equitably entitled. 

What is claimed is:
 1. A method of steering a drill rig, comprising: rotating a first wheel assembly to a first angle of rotation defining a perpendicular radial and rotating a second wheel assembly to a second angle of rotation defining a second perpendicular radial, the first angle of rotation and the second angle of rotation being selected such that the first perpendicular radial and the second perpendicular radial pass through a same point; and operating the first wheel assembly and the second wheel assembly to turn the rig about the point.
 2. The method of claim 1, wherein the point defines a central axis.
 3. The method of claim 2, wherein the central axis passes through a footprint the rig.
 4. The method of claim 1, wherein rotating the first wheel assembly is performed with a first steering mechanism and rotating the second wheel assembly is performed with a second steering mechanism.
 5. The method of claim 4, wherein the first and second steering mechanisms are the same steering mechanism and rotating the second wheel assembly comprises rotating the second wheel assembly in a direction opposite the rotating of the first wheel assembly.
 6. The method of claim 4, wherein the first steering mechanism and the second steering mechanism are separate steering mechanisms and rotating the second wheel assembly comprises rotating the second wheel assembly in a direction the same as the rotating of the first wheel assembly.
 7. The method of claim 1, further comprising deploying the first wheel assembly and the second wheel assembly prior to rotating each of the wheel assemblies.
 8. The method of claim 1, wherein rotating the first wheel assembly comprises: selectively engaging a wheel assembly with a steering mechanism in a starting position; rotating the wheel assembly with the steering mechanism; selectively disengaging the wheel assembly from the steeling mechanism; returning the steering mechanism to the starting position; reengaging the wheel assembly with the steering mechanism; and rotating the wheel assembly with the steering mechanism in a second direction.
 9. The method of claim 8, wherein the first direction is opposite the second direction.
 10. The method of claim 8, wherein rotating the second wheel assembly comprises rotating the second wheel assembly in a direction opposite that of the first wheel assembly.
 11. A method of steering a drill rig comprising a plurality of wheel assemblies, the method comprising: rotating each of the plurality of wheel assemblies about a vertical axis, the rotating defining a perpendicular radial for each wheel assembly of the plurality of wheel assemblies and the rotating comprising rotating such that the respective perpendicular radials of each wheel assembly all intersect at a single point; and operating the plurality of wheel assemblies to turn the rig about the point. 